How important magic is would depend on three factors I would think.

How does magic work?
Magic by its very nature falls under the rule of deus ex machina, so it needs to have rules lest anything goes. Personally I am a fan of settings where magic is an art rather than a talent. What I mean by this is that it involves an amount of time, energy and foresight, so simple magic could take minutes, and complex magic could take days, but the result would be god like. I also like when it is fast paced, think Last Avatar style.

What does magic do?
Since the bloodline has been watered down so to speak, it would be safe to say that magic becomes a specialty or better yet hereditary. So each magi has power over a specific aspect of magic. I'm thinking elemental, spiritual, divination, druidic (need to define what it means to be druid), healing, etc. Each one can be broken down further and further still. If this is not the case and magic lets you control the very fabric of the world, then I suppose power levels just dropped and where they were once able to move mountains, they can now only move stones, if magic was still a thing of course.

How many Maegi were there?
This is where importance is really determined. If the Maegi were less than 1% of the world, then the effects they had would not be too grand, but if all they created something that made life easier for everyone else, then the disruption would be much grander scale when what they created crumbled.

What I think is that after twenty years, the world would have adjusted well enough if magic wasn't the end all be all. Call it that the Conclave believed that man still needed to do for themselves and not rely on the power of the well. There would be those that abused their power, but the "good" Maegi would likely rise and route out the corruption if that happened. Maegi were likely sought out or made nobles so the capitals would feel it the most but the free cities may have only had one or two, so they would be relatively unaffected save for the world around them going to hell in a hand basket.

I would love to see what you already have for the setting, but getting on Skype can be problematic for me. The only thing I think needs to be flushed out are the cities, or at lease enough info for us to build them ourselves. So where they are in relation to one another, what their geography is like, what relations are like with each other, the type of government or number of people in power. The state of the country and its cities would be important to.